Process and apparatus of handling water which is contaminated with an oillike liquid

ABSTRACT

A liquid to be handled forms a body having a lower layer consisting of water substantially free of oillike liquid and an upper layer which comprises an oillike liquid. Water from said lower layer is pumped directly from said body. Liquid is pumped from said upper layer and is subjected to a separating treatment to remove oillike liquid.

[ 1 Sept. 17,1974

United States Patent Jakubek 1 1 PROCESS AND APPARATUS OF HANDLING Walker ct a1. Cruwford.......... Hobson,........ Smith..,. Muller Schmuuch et a1. Volker.........,....,...... Sheehy...........,.........

WATER WHICH IS CONTAMINATED WITH AN OILLIKE LIQUID [75] Inventor: Peter Jakubek, Brunn Am Gebirge,

Austria [73] Assignee: Fa. International Pollution Control Systems, Inc., Washington, DC.

July 8, 1971 ABSTRACT 18 Claims, 18 Drawing Figures Primary Examiner.10hn Adee Attorney, Agent, or Firm-Ernest G. Montague; Karl F. Ross; Herbert Dubno A liquid to be handled forms a body having a lower layer consisting of water substantially free of oillike liquid and an upper layer which comprises an oillike liquid. Water from said lower layer is pumped directly from said body. Liquid is pumped from said upper layer and is subjected to a separating treatment to remove oillike liquid.

BOld 29/36 Austria Austria Austria Stigall References Cited UNITED STATES PATENTS [22] Filed:

[21] Appl. No.: 160,779

[30] Foreign Application Priority Data July 13, 1970 Jan. 22. 1971 June 3, 1971 [52] US. [51] Int. [58] Field of Search......

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QM BY PROCESS AND APPARATUS OF HANDLING WATER WHICH IS CONTAMINATED WITH AN OILLIKE LIQUID This invention relates to a process of removing oil or the like from water which is contaminated with oil or the like, particularly from bilge water of ships, and to an apparatus for carrying out the process.

The dirty water pumped from merchant and pleasure ships has in most cases a high oil content. The contamination of coastal and inland waters by this dirty water has greatly increased in recent times. Water vehicles provided with inboard motors have a bilge, in which water of condensation, spent washing water, rainwater, and splashed water from leaks is collected. Oil also enters the bilge, e.g., from leaks of the motor or because oil has been spilled during an exchange of oil. As the bilge is pumped out, that oil is removed from the ship together with the dirty water.

Oil separators for larger ships are known but require a substantial maintenance, and the de-oiled water has only under favorable conditions the prescribed degree of purity of 20 milligrams oil per liter of water for inland waterways and 100 milligrams per liter of water on the sea.

Seagoing boats and yachts are required to have a bilge pump. Oil separators must not be connected in the bilge pump line.

lt is an object of the present invention to provide a process of removing oil or the like from water which is contaminated with oil or the like, particularly from bilge water of ships, which process enables an effective pumping of the water from the bilges and reliably prevents a pumping of water which has been contaminated with oil or the like from the ship.

It is another object of the invention to provide an apparatus for removing oil or the like from water which is contaminated with oil or the like, which apparatus is capable of treating water which is contaminated with oil or the like at relatively high rates, as is required on seagoing ships.

It is also an object of the invention to provide large spaces for collecting the oil which has been removed so that an emptying or maintenance of the oil separator is required only in relatively large intervals.

These objects are accomplished according to the invention in that water from the bilge of the ship is first pumped directly from the bilge of the ship, said pumping is interrupted before water is handled which is contaminated with oil or the like, and water which is contaminated with oil or the like, or oil or the like floating on such water, is pumped from the bilge through an oil separator and, if desired, through an air separator which precedes said oil separator.

The process according to the invention may also be characterized in that the change between a direct pumping from the bilge and a pumping from the bilge with removal of oil is controlled in dependence on'the liquid level in the bilge of the ship.

An apparatus for carrying out the process according to the present invention is substantially characterized in that the apparatus comprises a bilge pump which is controlled by a float-controlled switch, and a pump which pumps off water which is contaminated with oil through an oil separator and, if desired, through an air separator.

LII

It is also a feature of the present invention that the oil separator has a pressure-resisting housing, a filter for removing the oil or the like, a supply conduit which incorporates a non-return valve and serves to supply the water which is contaminated with oil, a discharge conduit for the purified water, and an air-venting valve, and the air space disposed in the oil separator over the liquid is under pressure.

In a preferred embodiment of the apparatus for carrying out the process according to the invention, bags of plastics material, which serve to receive the oil which has been removed, may be connected by two shut-off valves to the oil separator.

The oil separator which may be used in accordance with the invention is characterized in that it comprises a housing, an inlet pipe for oil, water, and air, which inlet pipe is provided with a check valve and has an outlet opening above the liquid level in the air separator, an outlet pipe which begins slightly over the bottom, and an air-venting valve, which is controlled in dependence on the liquid level and vents air from the air separator in response to a lowering of the liquid level in the air separator.

Another embodiment of the apparatus for carrying out the process according to the invention is intended for use in cases where the bilge water has only a small oil content, e.g., in sports boats. in that embodiment, a suction pipe ofa bilge pump or the like is surrounded by a substantially annular float, which comprises a filter ring and which is displaceable along the suction pipe, and an abutment plate is provided, which is spaced from the suction opening of the suction pipe and is arranged to be engaged by the underside of the filter ring when the liquid level in the bilge drops to such an extent that oil may be pumped.

According to another feature of the apparatus according to the invention, the float is connected to the filter ring and the float and filter ring consist of at least two parts each, which are adapted to be held together by an encircling band or the like.

One embodiment of the invention is substantially characterized in that the oil separator comprises at least one container for collecting oil which has been removed, at least one coarse separator, which may comprise a coarse filter, if desired, and at least on fine separator, which comprises a fine filter, the coarse separator being connected to the collecting container by an oil conduit, which incorporates a shut-off valve.

The major portion of the oil which has been removed collects in the coarse separator. To enable a transfer of oil from the coarse separator into the collecting container when a predetermined amount of oil has collected in the coarse separator, the shut-off valve is controlled in one embodiment of the invention by a twoposition float switch and a densimetric float, which floats in the coarse separator between the oil and the coarsely purified water.

In a further development of the invention, the coarse separator is adapted to be vented by a venting conduit which is adapted to be shut off by a shut-off valve and connected to the collecting container, and the shut-off valve is controlled by a magnetic float switch.

In order to enable a discharge of oil from the collecting containers and a feeding of said oil, e.g., to a furnace, and to enable a discharge of water which has collected in the collecting container, the latter may be adapted to be discharged through an outlet opening which is controlled by a magnetic float switch and the bottom of the collecting container may be provided with a valve-controlled discharge opening for any water which has been collected.

In a preferred embodiment of the invention, an intermediate settling tank, which may contain a coarse filter, is connected between the coarse separator and the fine separator.

To enable an economic manufacture of oil separators according to the invention for use under different operating conditions, the coarse separator, the fine separator and the intermediate settling tank may be contained each in a container which serves as a collecting container for the removed oil, and the units consisting, respectively, of a container and coarse separator, container and fine separator, and container and intermediate settling tank may constitute modules which may be assembled to form oil separators.

The use of this embodiment of the apparatus for removing oil or the like according to the present invention enables an adaptation of the oil separator to different operating conditions, e.g., in that a coarse separator is coupled to a plurality of fine separators, and any desired number of intermediate settling tanks may be connected between the coarse separator and the fine separators. The intermediate settling tanks may be connected in series and/or parallel.

According to another embodiment of the present invention, the containers for collecting the removed oil or the like may have a square configuration in plan.

A particularly space-saving arrangement will be achieved within the scope of the invention if the collecting container contains compartments for receiving the coarse separator, the fine separator and, if desired, the intermediate settling tank.

According to another feature of the present invention, the replacement of spent filters is facilitated in that all fittings associated with the coarse separator, the fine separator and the intermediate settling tank are mounted in the closing covers of the respective units so that the fittings can be removed from the housing of the coarse separator, the fine separator and the intermediate settling tank together with the covers thereof.

In oil separators according to the invention which are assembled from modules, the several collecting containers are interconnected by liquid conduits.

The filters used within the scope of the invention consist preferably of oil-resisting, lyophilic, open-cell foamed plastics material, e.g., of foamed plastics material consisting of polyesters or polyethers which contain isocyanates, diamines or glycols as cross-linking agents, or of polyurethanes or polyisocyanates. The pores of the foam forming the filters may be smaller as the depth of the filter increases.

The invention will now be explained more fully with reference to the drawings which show diagrammatically and by way of example several embodiments of the apparatus for carrying out the process according to the invention.

FIG. 1 shows a first embodiment of the apparatus for carrying out the process according to the invention.

FIG. 2 shows an oil separator such as is used within the scope of the invention.

FIG. 3 shows a mechanical float valve for controlling the venting of air, e.g., from the oil separator.

FIG. 4 shows the arrangement of the bags of plastics materials, which bags serve to collect the oil which has been removed.

FIG. 5 shows another embodiment of the apparatus for carrying out the process according to the invention.

FIGS. 6 and 7 are enlarged views showing the float provided with the filter ring in open and closed positions, respectively.

FIG. 8 shows by way of example an air separator such as is used within the scope of the present invention.

FIG. 9 is a sectional view showing an oil separator comprising an oil-collecting container, a coarse separator and a fine separator according to the present invention.

FIG. 10 shows a module of oil separators which are assembled from modules.

FIG. 11 is an elevation showing a modular oil separator consisting of a coarse separator and a fine separator.

FIG. 12 is a top plan view showing the oil separator of FIG. 11.

FIGS. 13 to 16 show different forms of oil separators assembled from several modules.

FIG. 17 shows a magnetic float switch.

FIG. 18 shows a switch controlled by a densimetric float.

The apparatus for carrying out the process according to the invention which is shown in FIG. 1 comprises essentially a filter supply pump 1, a bilge pump 3, and an oil separator 5. A main switch 12 is operated to start the bilge pump 3 and the filter supply pump 1. The two pumps first suck oil-free water from the bottom of a bilge 2. To prevent the bilge pump 3 from sucking oil from the surface of the water when the level of water in the bilge 2 drops, a magnetic float switch 4 is provided, which de-energizes the bilge pump 3 in time. If the bilge pump 3 is mechanically coupled to the drive motor, the magnetic float switch 4 may be arranged, e.g., to open a breather valve in the suction portion of a bilge conduit 13 so that the bilge pump 3 cannot suck more water.

Thereafter, only the filter supply pump 1 sucks and handles bilge water and finally the oil floating on the surface through a conduit 14 to the oil separator 5. Water from which oil or the like has been removed is discharged from the ship through a discharge conduit 6 for purified water. The filter supply pump 1 is a small self-priming pump, which has a capacity of about 2-10 liters per minute, depending on the size of the apparatus. Centrifugal pumps should be avoided because they agitate the fluids to form an oil-water emulsion, which can be separated only with difficulty, whereas this is not the case with gear or rotary pumps, which result in a less intense agitation.

A pressure-limiting switch 10 automatically deenergizes the filter supply pump when the pressure in the oil separator 5 exceeds a predetermined value, e.g., because the oil separator is clogged with dirt particles.

The oil separator 5 is tight and resists pressure, e.g., up to about 2 meters water for use on small yachts, so that it can be placed also below the design water line, as is particularly desirable.

All electric components of the apparatus shown in FIG. 1 are energized, e.g., by a battery 11, to which they are connected by the main switch 12.

The filters preferably consist of foamed plastics materials which can remove oil particles as the oilcontaminated liquids pass through the filter and which 2 cause the oil particles to become bonded and adsorbed on the surface of the filter material. The strength of that bond determines the efficiency of the separation of the oil and depends not only on the nature of the filter material but also on the arrangement of the filter and on the velocity of flow of the water to be purified through the filter. It has been found in tests that for a high efficiency of the separation of the oil the filter must be arranged in the separator in such a manner that the filter is always submerged in liquid so that there is a layer of liquid over the filter, and the liquid must flow through the filter from top to bottom. Besides, the velocity of flow through the filter must not exceed a certain value, which depends on the material of the filter. In a foam filter having a thickness of centimeters, that value is about 7 centimeters per minute. Finally, the pores of the foam filter preferably decrease in size downwardly, in the direction of flow.

The oil separator 5 shown in FIG. 2 consists substantially of a cover 29 and a container 18, which contains a foam filter 20. The container 18 consists desirably of translucent plastics material and is joined to the cover 29 by screw threads. The foam filter rests on a bottom screen 22, and the liquid level 16 in the oil separator 5 is slightly below the cover 29. A cushion 24 of air under pressure is left above said liquid level 16. The supply pipe 14 for oil-contaminated water and the drain pipe 6 for purified water are concentric to each other and firmly connected to the cover 29. The drain pipe 6 extends below the bottom screen 22. The foam filter 20 need not have a hole for the discharge pipe 6. The latter has at its lower end a conical tip 21, which penetrates into the foam filter 20 as the cover 29 is applied. This design ensures also a tight contact of the foam filter 20 with the drain pipe 6. Before the parts are assembled, the container 18 should be filled with water approximately to the liquid level designated 16.

Because the oil separator used according to the invention is tight and resists pressure, it may also be disposed below the water line so that the water can be forced through the oil separator.

The oil separator functions as follows: The oilcontaminated liquid is supplied through the conduit 14 to the oil separator 5 and is passed through the vertical supply pipe into the interior of the oil separator 5 and through a check valve 15 biased by a coil spring 26 flows into a liquid layer 25, which lies over the foam filter 20 and in which a coarse separation is effected because larger oil particles are entrained by the water flowing into the foam filter 20 and are retained by it sooner or later.

Tie oil-contaminated water passes finally through the bottom screen 22 and flows through openings 19 into the discharge pipe 6, where it rises and through that discharge pipe 6 is discharged from the container. The return check valve 15 prevents a draining of the oil separator 5 through the supply pipe 14 when the filter supply pump 1 is inoperative. In FIG. 2, the flow path of the oil-contaminated water is indicated by arrows 30 and the flow path of the purified water by arrows 31.

When the bilge is almost empty, the filter supply pump 1 sucks also air, which enters the oil separator 5 and continuously increases the size of the air cushion 24 so that the oil collected over the foam filter 20 may be forced by the air cushion 24 through the filter and finally through the discharge conduit 6 for purified water. To vent the air which has entered the oil separator 5, an air-venting solenoid valve 7 is provided, which receives an opening signal from a magnetic float switch 8 when the float 17 of said switch has lowered to a predetetermined extent because the surface of the liquid in the oil separator 5 has lowered from the level 16. The magnetic float switch 8 and the air-venting solenoid valve 7 are connected to the battery 11 and the main switch 12 by leads 27 and 28. The flow path of the air through the air-venting valve 7 is indicated by arrows 23 and 23'.

In another embodiment of the apparatus according to the present invention, the air-venting solenoid valve 7 controlled by a magnetic float switch 8 may be replaced by a mechanical float valve, such as is shown in FIG. 3. The float valve comprises a float lever 33, which is pivoted in a bearing 32 and which is provided at one end with a float 35. The other end of the float lever 33 is operatively connected to a valve 34, which when open permits air to flow out of the oil separator 5 along the arrows 23, 23. The bearing 32 is secured to the cover 29 of the oil separator 5.

Large oil droplets are collected at the surface 16 of the liquid to form a continuously growing oil layer, which finally occupies the entire liquid layer 25 and then enters the foam filter 20 itself. If the container 18 consists of transparent plastics material, the growth of a dark-colored oil layer can be distinctly observed from the outside.

Experiments have shown that the foam filters 20 when used in yachts may have a life of up to several years if the oil which has been removed by the coarse separation is discharged in time so that it cannot enter the foam filter 20. In this case, the life of the filter will be determined by the clogging of the pores of the filter with dirt particles which deposit on the filter and in the pores thereof, rather than by the contamination of the filter with oil. The life of the foam filter can be much increased if the layer of collected oil is removed before. It has also been found that during periods in which the oil separator is inoperative, oil droplets which have collected from the uppermost filter layer, having coarse pores, rise and enter the oil layer which floats on the liquid layer 25. Hence, the foam filter will clean itself when the apparatus is inoperative. If the collected oil is permitted to grow into the foam filter 20 rather than being drained, oil-free water (containing less than 20 milligrams oil per liter of water) will be discharged even if the oil-contaminated layer of the foam filter extends almost to the bottom screen 22.

Particularly on sports boats, the oil-contaminated layer in the foam filter 20 is preferably permitted to grow to a mark 9, which is provided on the housing 18 and which indicates that the foam filter has been spent and must be replaced. Depending on the rate at which oil is collected, that condition may already be reached in one season. To replace the foam filter, the screw cover 29 together with the fittings and devices mounted therein is unscrewed and removed. The remaining container 18 with the oil-soaked foam filter 20 is closed with a conventional cover and deposited at a service station or in the installation where the ship is kept during the winter. In service stations, that work can be performed and a check can be made whether the filter is already spent. The new foam filters which are available, e.g., from service stations and contained in containers 18 are simply screwed to the cover 29 so that the apparatus is again ready for use.

The filter container and the screen bottom may be made at low cost from combustible plastics material so that the closed containers containing the spent filters may be collected and may be burnt in furnaces.

In this way, the filters can be replaced in a clean operation and the waste oil can hardly be spilled. Besides, there will be an assurance that collected waste oil is not wilfully thrown over board.

More waste oil will be collected in small merchant ships than in yachts, as a rule. To avoid a need to replace the filter container 18 with the foam filter in intervals which are too short, the dirty oil collected in it may be discharged into a larger collecting tank from time to time before the oil layer reaches the foam filter.

FIG. 4 shows an embodiment of the invention in which a plurality of bags 37 of plastics material are secured to the container 18. These bags are very flat, like bags for storing blood, so that they occupy only a small space. These bags 37 of plastics material are welded to or tightly fitted on oil discharge pipes 39, which open into the container 18. There will be one plug valve 36 at the pipe 39 and one at the neck of the bag 37 of plastics material. The amount of oil collected in the container 18 can easily be checked because the container 18 consists of translucent plastics material. When a large amount of oil has been collected in the container 18, the two plug valves 36 are opened so that oil can flow into a bag 37 of plastics material. This flow of oil is assisted by the air cushion 24, which is under pressure and disposed over the liquid 25. The two plug valves 36 are then closed and the neck of the bag 37 of plastics material is severed at 38, between the plug valves 36. The neck of the bag 37 may be prepared in any desired manner for being severed at the line of severance 38. The oil-filled bag 37 of plastics material may be burnt in a furnace or may simply be delivered on land. The number of bags 37 of plastics material may be selected to match the life of the foam filter 20 so that the consumption of all bags 37 of plastics material indicates that the foam filter 20 has been spent.

An apparatus for carrying out the process according to the invention will now be described with reference to FIGS. 5 to 7. This apparatus is particularly suitable for small sports boats. Only very small amounts of oil enter the bilges of small sports boats and only a thin film of oil is formed on the surface of the water. When the bilge is pumped out, only a fraction of the oil floating on the surface is removed from board. The residual oil deposits on the bottom of the bilge and adheres there. For this reason, the bilges must be thoroughly cleaned in the winter, when the boards are placed on land. For this reason, a simple apparatus is sufficient,

which is attached to the suction head of the bilge pump and prevents a pumping of the oil film from board.

FIG. 5 is a diagrammatic view of such apparatus. The same comprises the bilge pump 3 provided with a suction pipe 13, on which a float 40 is longitudinally slidably mounted. A filter ring 41 is secured to the suction pipe. The lower end of the suction pipe 13 is provided with an abutment plate 42 and together with the float 40 and the filter ring 41 is surrounded by a protective screen 43.

FIG. 6 is an enlarged view showing the cylindrical float 40, which on its underside carries the filter ring 41. The latter is made, e.g., from open-cell foamed plastics material. FIG. 6 illustrates a condition in which there is a high level of water in the bilge so that the float 40 and the filter ring 41 float and oil-free water from the bottom can be sucked freely through the suction pipe 13 of the bilge pump 3.

When the surface of the liquid level in the bilge 2 drops below a predetermined level so that oil which floats on the surface may also be sucked, the filter ring 41 will assume the position shown in FIG. 7 and in which the filter ring 41 engages the abutment plate 42, which is spaced from the suction opening of the suction pipe 13. The bilge water is now constrained to pass through the foam filter 41 along the arrows 48 before it enters the suction pipe 13 in the direction of the arrows 47 when the oil has been removed from the water. In that case, oil particles are retained in the filter ring 41.

An annular cavity 44 is defined between the filter ring 41 and the suction pipe 13 and holes 45 which extend parallel to the suction pipe 13 open into said cavity and enable a sucking of the bilge water without removal of oil when the float 40 provided with the filter ring 41 has not lifted from the abutment plate 42 although there is a high level of water in the bilge.

The holes 45 also ensure that the water will flow slowly through the filter ring 41, as is required for an efficient filter action. This is due to the fact that air is sucked through said holes 45 in the direction of the arrows 46 so that the vacuum in the annular space 44 does not become excessive.

The filter ring 41 must be replaced from time to time because it becomes soaked with oil. The filter ring 41 is preferably replaced in a service station by the attendant thereof. It is desirable to replace together with the filter ring 41 the float 40, which may be made from inexpensive plastics material or from closed-cell hard foam. According to the invention, the float 40 and the filter ring 41 may consist each of two halves, which are held together by an encircling band 61 so that a satisfactory replacement is facilitated.

The air which is sucked when the bilge has been almost emptied may be removed in a separate air separator, which is connected between the filter supply pump and the oil separator. In that case, the need for the airseparating means at the cover 29 of the oil separator is eliminated. These means consist of the magnetic float switch 8 and the air-venting solenoid valve 7. When the oil separator is under pressure because it is disposed under the water line (design water line), the air separator must also be under pressure. In many cases, space restrictions prevent an arrangement of the oil separator and the air separator above the water line.

A particularly desirable air separator for use under the water line is shown in FIG. 8. The air separator 50 comprises a pressure-resisting container 51, which has a cover that is provided with a supply conduit 52 for oil, water, and air, a check valve 53 in the conduit 52, and a discharge conduit 54 for oil and water. The discharge conduit 54 leads to the succeeding oil separator. The cover is also provided with a magnetic float switch 57 and an air-venting solenoid valve 58, which are connected by leads 59 and 60, respectively, to the main switch and battery.

Air, water and oil flow through the supply conduit 52 into the air separator 50, which contains in its upper portion a cushion 56 of compressed air. Oil and water 55 collect under the air cushion and under the pressure of the air cushion 56 flow through the discharge conduit S4 to the oil separator. The air which enters through the supply conduit 52 depresses the surface of the liquid until the magnetic float switch 57 opens the air-venting solenoid valve 58 when the surface of the liquid has been lowered to a predetermined level. Air is then allowed to escape through the valve 58 until the surface of the liquid has risen and the magnetic float switch 57 closes the air-venting solenoid valve 58. These operations are continually repeated. The limit defined by the magnetic float switch 57 and the height of the container 51 must be matched so that no air can escape through the discharge conduit 54 even during a pulsating discharge of the pump.

In the air separator, all fittings as well as the supply and discharge conduits are provided at the cover and can be removed together with the same.

A mechanical float valve such as is shown in FIG. 3 may be provided instead of the magnetic float switch 57 and the air-venting solenoid valve 58.

The oil-separating filter used within the scope of the invention consists preferably of an oil-resisting, opencell, foamed plastics material, e.g., of polyesters or polyethers which contain isocyanates, diamines or glycols as cross-linking agents, or of polyisocyanates or the like. Other filters may also be used within the scope of the invention, which like the above-described foam filter selectively retain the oil or the like which is contained in water whereas the latter flows through the filter substantially without restriction.

The oil separator according to the invention which is shown in FIG. 9 comprises an oil-collecting container 101, a coarse separator 102, and a fine separator 103. The oil-collecting container 101 serves to collect the oil 119 that has been removed in the coarse separator 102 and is laterally provided with an oil discharge valve 118, which is controlled by a magnetic float switch 117, to which the valve 118 is connected by an electriclead 122. The oil-collecting container 101 is provided at its top with an air-venting opening 105 and in its bottom with a valved discharge opening 132 for any water 120 which may have collected in the oil-collecting container 101. The oil-collecting container 101 comprises two compartments 116 for accommodating the housings 115 of the coarse separator 102 and the fine separator 103, respectively.

The coarse separator 102 shown in FIG. 9 comprises the separator housing 115, which is closed by a cover 141, and fittings mounted in the cover 141, such as the supply and discharge conduits for the water to be purified, discharge conduits for oil and air, and two float switches. Specifically, the cover 141 ofthe coarse separator 102 is provided with a bilge water supply conduit 106, which is provided at its lower end with a baffle plate 108, moreover, a discharge conduit 109 for coarsely purified water, an air-venting conduit provided with a shut-off valve 124, an oil discharge conduit 129, which is adapted to be shut off by a solenoid valve 130, and two float switches 125 and 126.

The magnetic float switch 125 is connected by conduits 123 with the air discharge valve 124. The airair cushion 121 disposed over the oil layer 119. The

densimetric float 127 of the float switch 126 is trimmed to float between the oil layer 119 and the water layer 120. The float of the solenoid switch 125 floats on the oil layer 119. The separator housing of the coarse separator 102 contains a coarse filter 113, which is carried by a screen bottom 114. Just as the coarse separator 102, the fine separator 103 consists of the separator housing 115 and the cover 141. A supply conduit 110 for prepurified water opens from above into the fine separator. A baffle plate 111 is provided to avoid a direct flow of the water against a filter 112, which is contained in the fine separator 103. The filter 112 in the fine separator 103 has various pore sizes, and the pore size may decrease in a downward direction. The filter 112 may consist, e.g., of three layers having different pore sizes. Alternatively, filters 112 may be composed of more or less than three layers having different pore sizes.

The filter material for the filters 112 and 113 consists preferably of the foam which has been described hereinbefore.

The fine separator 103 comprises also a screen bottom 114, which carries the foam filter 112, and a discharge conduit 107 for the now purified water. During the operation of the oil separator, the fine separator 103 contains a water layer 120, which is disposed over the filter layer 112, a small oil layer 119 floating on the water layer 120, and an air cushion 121 on top.

The oil separator according to the invention has the following mode of operation:

Bilge water which is contaminated with oil or the like and which may contain entrained air is supplied through the conduit 6 in the direction of arrows 133 into the coarse separator 102. A first separation into the water level 120, the oil level 119 and the air cushion 121 is effected in the coarse separator 102. Under the pressure of the bilge water which is contaminated with oil or the like and which is subsequently supplied, and under the force of gravity, prepurified water flows in the direction of arrows 135 through the coarse filter 113 and leaves the coarse separator through the discharge conduit 109. The prepurified water then flows in the direction of the arrows 135 through a transfer conduit 104 between the coarse separator 102 and the fine separator 103 and through the supply conduit 110 into the fine separator 103. A further separation into the water layer and the oil layer 119 is effected in the upper part of the fine separator 103. Under the pressure of the prepurified water which is subsequently supplied and under the force of gravity, the water layer 120 flows through the filter 112 and is discharged from board through the discharge conduit 107 in the direction of the arrow 136. The oil layer 119 in the coarse separator 102 grows continuously so that the densimetric float 127 floating between the oil layer 119 and the water layer 120 descends. The solenoid switch 126, which controls the solenoid valve 130 through conduit 131, defines two limits. The solenoid valve 130 is opened at the lower limit and is closed at the upper limit. When the float 127 has reached the lower limit defined by the float switch 126, the solenoid valve 130 is opened and oil can flow through the oil discharge conduit 129 in the direction of arrow 134 into the oilcollecting container 101.

This is continued until the float 127 reaches the upper limit for the float switch 126 and the solenoid valve 130 is closed.

The magnetic float switch 125 controls in a similar manner the air-venting valve 124 in the air conduit 128. As a result, any air which is entrained by the bilge water is vented through the conduit 128, the oilcollecting container 101, and the venting conduit 105 so that the air cushion 121 in the coarse separator 102 cannot grow beyond a predetermined size.

When a certain amount of oil 119 has collected in the oil-collecting container 101, the magnetic float switch 117 operates the,.oil discharge valve 118 and oil is discharged from the oil-collecting container 101. That discharged oil is preferably directly supplied to a furnace. This embodiment of the apparatus according to the invention has the advantage that the oil is collected in larger amounts so that it can be burnt economically.

The apparatus according to the invention has the additional advantage that only relatively small amounts of oil are collected in the fine separator 103 so that the filter 112 in the fine separator has a long life. When the bilge water contains much oil, an intermediate settling tank may be connected betweenthe coarseseparator 102 and the fine separator 103. In this case, the coarse separator 102 contains no filter 113. A filter may be provided, for instance, in the intermediate settling tank, which may be very simple in structure and basically similar to the fine separator. It is also apparent from FIG. 9 that the separator housings 115 of the fine and coarse separators as well as the separator housing of any intermediate settling tank are similar in structure.

FIG. 10 shows a single module 140 for the modular system which has been proposed according to the invention for the assembling of oil separators for use under various operating conditions. The module 140 comprises a container 138, which serves as an oilcollecting container and into which the separator housings 115 are inserted, which contain a coarse separator 102, a fine separator 103 or an intermediate settling tank. FIG. 11 shows strictly diagrammatically how an oil separator may be assembled from modules consisting only of a coarse separator 102 and a fine separator 103. The two containers 138 are connected at the bottom by a transfer conduit 139 so that both containers 138 are available as oil-collecting containers.-

The containers 138 are preferably square in plan, although other configurations in plan may also be used, provided that they enable an assembling of the several modules 140 within a small space.

FIG. 12 is a diagrammatic top plan view of the oil separator which is shown in FIG. 11 and has been assembled from modules.

FIG. 13 shows an oil separator which has been assembled from modules consisting of a coarse separator 102, a fine separator 103 and an intermediate settling tank 137. The three modules are connected in series b transfer conduits.

FIG. 14 shows diagrammatically the design of an oil separator container which comprises two intermediate settling tanks 137, which are connected in series between the coarse separator 102 and the fine separator 103.

An arrangement such as shown in FIG. 15 is recommended when oil is collected at a high rate and the water discharged by the oil separator is required to have a particularly high purity. This arrangement comprises a coarse separator 102, two intermediate settling tanks 137 and two fine separators 103. The intermediate settling tanks 137 and the fine separators 103 are fed by the coarse separator 102 and connected in parallel so that a particularly good purifying effect is achieved and spent filters may be replaced in alternation during the operation. In that case, a pair of units consisting of an intermediate settling tank 137 and a fine separator 103 must be shut off for a short time.

In the arrangement shown in FIG. 16, the coarse separator 102 comprises two parallel chains, each of which comprises two intermediate settling tanks 137 and one fine separator 103. Such an oil separator may easily be assembled from modules 140 and suggests the large number of possibilities which are available and is intended, e.g., for bilge water having a particularly large oil content.

The parallel connection of the intermediate settling tanks 137 and fine separators 103 increases the crosssection which is available so that even when water is handled at a high rate, e.g., during the emptying of ballast tanks, the velocity of flow in the filter layer will be sufficiently low for a high efficiency of separation of oil according to the equation of continuity, which says that the rate at which liquid flows through a cross-section is proportional to the area F of said cross-section and the velocity v at which the fluid flows through said crosssection (F X v const.).

The basic design of the magnetic float switches 117 and 125 is apparent from FIG. 17, which shows the magnetic float switch 117 for controlling the oil discharge valve 118. The conduits 122 terminate in the housing of the magnetic float switch 117 in contacts 144. A contact plate is disposed under the contacts 144 and mounted on a spring 146. FIG. 17 shows the switch in its open position, in which the float 142 provided with a magnetic ring 143 is below the contact plate 145 so that the latter does not bridge the contacts 144. When the oil level 119 rises, the contact plate 145 is raised by the magnetic ring 143 so that the contacts 144 are bridged and the circuit which controls the oil discharge valve 118 is closed.

FIG. 18 shows details of the float switch 126 which comprises the densimetric float 127. The latter is trimmed to float under the oil layer 119 but on the water 120. Two magnetic switches 149 and 149' are disposed in the tubular housing 148 of the float switch 126. The lower magnetic switch 149 controls the opening and the upper magnetic switch 149' controls the closing of the solenoid valve 130 which is incorporated in the oil conduit 129. Each of the magnetic switches 149 and 149' comprises a hollow glass body, which has a beanlike shape and is filled with a protective gas and in which resilient contacts 150 are fused. When the contacts 150 are disposed within the magnet 147, which has, e.g., the shape of a ring, the contacts 150 move against each other to close the circuit which controls the solenoid valve 130. The annular magnet 147 in the float 147 may be replaced by one or more rodshaped magnets.

What is claimed is:

1. Apparatus for separating oil from water constituting a liquid from a hold, comprising a first pump means positioned for directly pumping out water from said hold,

a control switch means in dependency on the level of the liquid in said hold for switching off said first pump means,

an oil separator,

a second pump means positioned for pumping out of said hold water mixed with oil and on the latter a layer of oil, respectively, and to said oil separator,

nicating with pure water separated in said container for removing said pure water,

means for switching off said first pump and switching over from said first pump to said second pump, respectively,

an air venting valve means for reducing the pressure of said air cushion,

a switching means for controlling said air venting valve corresponding to a lowering of the level of said liquid in said space in said oil separator, and

said supply pipe said drain pipe, said air vent valve, and said switching means received in said cover of said container.

2. Apparatus as set forth in claim 1, in which said filter packing consists of a material selected from the class which consists of polyurethanes, polyisocyanates, cross-linked polyesters and cross-linked polyethers, which polyesters and polyethers contain a cross-linking agent selected from the class consisting of isocyanates, diamines, and glycols.

3. The apparatus, as set forth in claim 1, wherein said drain pipe extends to below said filter packing and terminates at a free end in a point.

4. The apparatus, as set forth in claim 1, wherein said oil filter packing is made of foam material, having open pores, said pores become smaller with progressing depth. 5. The apparatus, as set forth in claim 1, wherein said switch means for controlling said air venting valve is a magnet float switch.

6. The apparatus, as set forth in claim 1, wherein said container is made of transparent synthetic material and is equipped with a marker means for indicating the exhaust of said filter packing.

7. The apparatus, as set forth in claim 1, further comprising two plug valves,

bag means of synthetic material are connected with said oil separator by means of an opening portion of said bag means and of said oil separator for receiving the separated oil over said two plug valves,

the latter being operatively disposed in said opening portion. 8. The apparatus, as set forth in claim 7, wherein said bag means engage prior to their filling with the separated oil on said container of said oil separator,

a severance means disposed between said two plug valves for the separation of said bag means when filled.

9. The apparatus, as set forth in claim 1, further comprising an air separator means operatively connected to said oil separator.

10. The apparatus, as set forth in claim 9, wherein said air separator means is disposed between said second pump means and said oil separator, and has a housing and an inlet pipe for oil, water and air, said inlet pipe entering into said housing into the interior of said air separator means and terminating above a liquid level inside of said air separator means at one end of said inlet pipe,

a second check valve, positioned at said one end of said inlet pipe,

an outlet pipe exiting from said air separator means and beginning above the bottom of said air separator means, and

an air release valve means controlled by the liquid level in said air separator means and comm unicating with an upper inside portion of said air separator means for removing air released from the latter by means ofa lowering of the liquid level in said air separator means.

11. The apparatus, as set forth in claim 1, wherein said air release valve means is an electromagnetic valve, and

a magnet float switch means for controlling said air release valve means.

12. The apparatus, as set forth in claim 1, further comprising at least one collection container positioned for receiving removed oil from said oil separator,

said oil separator includes at least one coarse separator and at least one fine separator with said filter packing for the separation of the oil,

said coarse separator is connected by conduit means with said fine separator, and said coarse separator is connected with said at least one collection container by means of an oil conduit, a locking valve means for closing off said oil conduit,

13. The apparatus, as set forth in claim 12, wherein said floating switch means is a magnetic float switch, and an air venting valve float switch means constituting a magnetic float switch. 14. The apparatus, as set forth in claim 12, further comprising an outlet valve means for said at least one collection container for emptying the latter,

15 4 16 a magnet swim switch means responding to the insaid fine separator, respectively, constituting modcrease of liquid level in said collection container ules capable of being set up in accordance with a and for controlling said outlet valve means, and modular building system. a lockable emptying opening at the bottom of said 17. The apparatus, as set forth in claim 16, wherein collection container. 5 15. The apparatus as set forth in claim 12, further individual containers are connected among each comprising other by means of liquid conduit means connecting said at least one intermediate setting container under circollection containers.

cumstances said coarse separator contains a coarse 18. The apparatus, as set forth in claim 13, wherein filter packing of foam material, and said intermediate setting container is switched besaid coarse separator and said fine separator are distween said coarse separator and said fine separator. posed in said collection container, cover means for said coarse separator and said fine separator, and 16. The apparatus as set forth in claim 12, wherein said conduit means, said oil conduit, said floating said coarse separator and said fine separator are disswitch means and said air venting float switch posed in one container formed as a collection conmeans being operatively connected to and through tainer for the separated oil, and said cover means. said collection container, said coarse separator, and 

1. Apparatus for separating oil from water constituting a liquid from a hold, comprising a first pump means positioned for directly pumping out water from said hold, a control switch means in dependency on the level of the liquid in said hold for switching off said first pump means, an oil separator, a second pump means positioned for pumping out of said hold water mixed with oil and on the latter a layer of oil, respectively, and to said oil separator, said oil separator comprising, a pressure-tight container having a cover, a filter packing disposed therein for separating said oil, and, spaced from a top of said container, forming inside said container a top space for liquid, an air cushion, the latter standing under pressure and lying above the liquid, a supply pipe entering said container and operatively connected to said second pump means, a check valve operatively connected to said supply pipe, and a drain pipe exiting from said container and communicating with pure water separated in said container for removing said pure water, means for switching off said first pump and switching over from said first pump to said second pump, respectively, an air venting valve means for reducing the pressure of said air cushion, a switching means for controlling said air venting valve corresponding to a lowering of the level of said liquid in said space in said oil separator, and said supply pipe said drain pipe, said air Vent valve, and said switching means received in said cover of said container.
 2. Apparatus as set forth in claim 1, in which said filter packing consists of a material selected from the class which consists of polyurethanes, polyisocyanates, cross-linked polyesters and cross-linked polyethers, which polyesters and polyethers contain a cross-linking agent selected from the class consisting of isocyanates, diamines, and glycols.
 3. The apparatus, as set forth in claim 1, wherein said drain pipe extends to below said filter packing and terminates at a free end in a point.
 4. The apparatus, as set forth in claim 1, wherein said oil filter packing is made of foam material, having open pores, said pores become smaller with progressing depth.
 5. The apparatus, as set forth in claim 1, wherein said switch means for controlling said air venting valve is a magnet float switch.
 6. The apparatus, as set forth in claim 1, wherein said container is made of transparent synthetic material and is equipped with a marker means for indicating the exhaust of said filter packing.
 7. The apparatus, as set forth in claim 1, further comprising two plug valves, bag means of synthetic material are connected with said oil separator by means of an opening portion of said bag means and of said oil separator for receiving the separated oil over said two plug valves, the latter being operatively disposed in said opening portion.
 8. The apparatus, as set forth in claim 7, wherein said bag means engage prior to their filling with the separated oil on said container of said oil separator, a severance means disposed between said two plug valves for the separation of said bag means when filled.
 9. The apparatus, as set forth in claim 1, further comprising an air separator means operatively connected to said oil separator.
 10. The apparatus, as set forth in claim 9, wherein said air separator means is disposed between said second pump means and said oil separator, and has a housing and an inlet pipe for oil, water and air, said inlet pipe entering into said housing into the interior of said air separator means and terminating above a liquid level inside of said air separator means at one end of said inlet pipe, a second check valve, positioned at said one end of said inlet pipe, an outlet pipe exiting from said air separator means and beginning above the bottom of said air separator means, and an air release valve means controlled by the liquid level in said air separator means and communicating with an upper inside portion of said air separator means for removing air released from the latter by means of a lowering of the liquid level in said air separator means.
 11. The apparatus, as set forth in claim 1, wherein said air release valve means is an electromagnetic valve, and a magnet float switch means for controlling said air release valve means.
 12. The apparatus, as set forth in claim 1, further comprising at least one collection container positioned for receiving removed oil from said oil separator, said oil separator includes at least one coarse separator and at least one fine separator with said filter packing for the separation of the oil, said coarse separator is connected by conduit means with said fine separator, and said coarse separator is connected with said at least one collection container by means of an oil conduit, a locking valve means for closing off said oil conduit, a floating switch means for opening and closing, respectively, said locking valve means and having two switching points responsive to the rising or lowering of a limit range between oil and water in said coarse separator, and a densimetric float body floating in said coarse separator between said oil and the water operatively connected to said floating switch means.
 13. The apparatus, as set forth in claim 12, wherein said floating switch means is a magnetic float switch, and an air venting valve float switch means constituting a magnetic float switch.
 14. The apparatus, as set forth in claim 12, further comprising an outlet valve means for said at least one collection container for emptying the latter, a magnet swim switch means responding to the increase of liquid level in said collection container and for controlling said outlet valve means, and a lockable emptying opening at the bottom of said collection container.
 15. The apparatus as set forth in claim 12, further comprising at least one intermediate setting container under circumstances said coarse separator contains a coarse filter packing of foam material, and said intermediate setting container is switched between said coarse separator and said fine separator.
 16. The apparatus as set forth in claim 12, wherein said coarse separator and said fine separator are disposed in one container formed as a collection container for the separated oil, and said collection container, said coarse separator, and said fine separator, respectively, constituting modules capable of being set up in accordance with a modular building system.
 17. The apparatus, as set forth in claim 16, wherein individual containers are connected among each other by means of liquid conduit means connecting said collection containers.
 18. The apparatus, as set forth in claim 13, wherein said coarse separator and said fine separator are disposed in said collection container, cover means for said coarse separator and said fine separator, and said conduit means, said oil conduit, said floating switch means and said air venting float switch means being operatively connected to and through said cover means. 